Initially I thought I would need 3/5 N for this to work so I basically shelved this clear for several months.
Since there’s nothing going on in masters at the moment I decided to revisit this. I spent a fair amount of time getting this to work, I had numerous attempts come very close (to the point where he would die at the end from trap/burn, but it doesn’t give you the win if he kills your last unit). Finally I figured out that the clear hinges on killing the Celebi on the post-sync grassy glide. This allows Brendan to fit another TM in, giving a higher powered B-move at the end.
I also got a bit lucky with a tower cookie for Brendan that gave him CS3, I’m sure that helped here as well.